Violence against children is widespread and tolerated around the world, a report by the UN has said.
The UN wants all governments to deal with the problem
A four-year study to be presented in New York says many youngsters faced physical abuse that was either hidden or socially approved.
Almost six million children have been forced into work and many more have become prostitutes, the UN said.
In a separate report, Save the Children said more than a million children worldwide were imprisoned.
The British-based charity said its global research showed 90% of those imprisoned were found guilty of minor offences.
The UN set out to paint a detailed picture of the nature, extent and causes of violence against children - and then recommend ways to stop it.
It is the first time the organisation has attempted to study the issue on a global scale.
The report's authors found that more than one billion children around the world could still be beaten legally by their teachers.
Other statistics outline sexual abuse, domestic violence and the treatment of children being held in detention.
The author of the report, Professor Paulo Sergio Pinheiro, told BBC News it was time for children to have the same rights under law as adults.
"This is the moment to recognise children as being protected by rights, as full citizens, and not as mini-human beings or the property of their families," he said.
He compared the plight of children with the emancipation of women in the 20th Century and of workers in the 19th.
The report's authors said they were encouraged by the participation of governments from across the globe.
The UN has now recommended that every nation should now have a national strategy to prevent violence against children.
A third report published on Tuesday by Amnesty International was fiercely critical of the way thousands of children in the DR Congo were still in the hands of armed gangs, three years after the war.